1. Field of the Invention
This invention relates to improvements in an airbag restraint system for protecting a vehicle passenger in a vehicle serious collision, and more particularly to an airbag which is formed integrally by weaving without a sewing operation.
2. Description of the Prior Art
A variety of airbag restraint systems for automotive vehicles have hitherto been proposed and put into practical use in order to protect a vehicle passenger in the event of a vehicle serious collision or the like. Such airbag restraint systems are disclosed, for example, in Japanese Patent Publication No. 56-43890, Japanese Utility Model Publication No. 54-2521 and Japanese Utility Model Provisional, Publication No. 61-185642.
These airbag restraint systems are usually arranged as set forth below. The airbag restraint system includes an airbag which is momentarily inflated upon being filled with high pressure gas from a gas generator in the event of a serious collision or the like. The airbag is usually constituted of circular front and rear side sheet members which are formed of cloth material. The front and rear side sheet members are sewed at their peripheral portions with each other thereby to be formed into the bag-shape. The rear side sheet member is formed at its central part with a gas inlet through which gas from the gas generator is supplied into the airbag.
Additionally, the airbag is provided therein with a plurality of suspension belts for the purpose of preventing the airbag from directionally inflating or from projecting generally in one direction or toward the vehicle passenger during inflation of the airbag upon being supplied with the gas. Each suspension belt is sewed at its one end section with the inner surface of the front side sheet member, and at the other end section thereof with the inner surface of the rear side sheet member to form an installation section. This installation section is tightly held between a retainer and a base plate, which is fixedly secured to a vehicle stationary member, such as an instrument panel or a steering wheel.
However, drawbacks have been encountered in such a conventional airbag restraint system, as discussed hereinafter. The front and rear side sheet members are usually formed by circularly punching an original sheet material. The original sheet material is prepared by coating a plain weave fabric with a synthetic resin layer. Then, the thus obtained circular front and rear side sheet members are sewed to each other at their outer peripheral sections with each other to become bag-shaped. During sewing, sewing machine needles will injure fibers of weaving yarns of the plain weave fabric and cause the weaving yarns to be broken. This leads to a possibility that the joining strength between the front and rear side sheet members are lowered. Additionally, a sewing operation makes it difficult to obtain a uniform airbag shape in manufacturing airbags, while being complicated and troublesome, thereby to raise the production cost of the airbag.